Field of the Invention
The present techniques relate to a Group III nitride semiconductor light-emitting device intended for relaxing stress applied to a light-emitting layer, and a production method therefor.
Background Art
Some semiconductor light-emitting devices have an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer. The light-emitting layer is a layer which emits light through recombination of holes and electrons. Stress is sometimes applied to the light-emitting layer from the n-type semiconductor layer and the p-type semiconductor layer between which the light-emitting layer is interposed. When stress is applied to the light-emitting layer, the light-emitting layer is distorted accordingly. The overlapping of wave functions of electrons and holes in the light-emitting layer is reduced, thereby decreasing the recombination rate of electrons and holes. That is, the light quantity of the semiconductor light-emitting device is reduced.
To relax the stress applied to the light-emitting layer, the techniques to form an n-side superlattice layer in the n-type semiconductor layer have been developed. For example, Japanese Patent Application Laid-Open (kokai) No. 2009-260398 discloses an n-side superlattice layer which is an alternating layer of InXGa1−XN (first layer) and InXGa1−XN (second layer), wherein the thickness of the first layer is half the thickness of the second layer, and the total thickness of the first layer and the second layer is less than 70 Å.
When a plurality of pits is formed at least from the n-type semiconductor layer to the light-emitting layer, stress applied to the light-emitting layer can be further relaxed. When pits are formed in the semiconductor layer, the semiconductor layer may be abnormally grown with the pits as starting points. Therefore, a Group III nitride semiconductor light-emitting device exhibiting improved crystallinity while suppressing abnormal growth of semiconductor layer due to pits and a production method therefor are expected.